Evacuation of citizens from flooding conditions has always been problematic. The problems were well illustrated during the flooding of New Orleans in the aftermath of Hurricane Katrina. In this situation a large portion of the population were stranded in waters that may be shallow in some areas, but otherwise posed a dangerous risk due to contaminated water concealing submerged objects and low power lines. Even if the water was considered deep, the use of conventional watercraft proved to be most problematic as the outboard engines would strike a submerged obstacle such as a mailbox, automobile, and so forth. A conventional outboard engine is designed for navigable waters. If an outboard engine strikes an object, the propeller is designed to spool which protects the drive shaft but renders the motor useless for propulsion. Having personally spent nearly thirty years in the Coast Guard, I am well aware of the dangerous conditions facing emergency evacuations and the lack of proper evacuation equipment.
Unique to the boating industry is the Personal Water Craft (PWC) which relies upon a propulsion system capable of operating in shallow water by use of a jet drive. Jet drives employ an inboard engine that drives a pump jet having a screw shaped impeller to create thrust for propulsion and steering. The PWC, also known by some of the brand names such as Wave Runner, Jet Ski, or Sea-Doo are designed to carry only one or two people at a time. In an emergency situation, such as Katrina where flood waters were rising, the PWC provided the ideal propulsion system but lacked the capacity to evacuate the large amount of people in a short period of time. For these reasons, helicopters were brought in making evacuation extremely risky (i.e. hoisting cable in close proximately to a power line) and expensive.
PWC are very affordable and sold in such large numbers that a new for sale or used/private PWC can be found in most any neighborhood. Thus, while a propulsion system has been found to be readily available within a given area, it lacks the ability to move a large amount of people in a short amount of time.
Various attempts to provide watercraft for shallow use can be found in the following patents. U.S. Pat. No. D438,506 discloses an ornamental design for a tunnel hull catamaran landing craft.
U.S. Pat. No. 4,836,298 discloses catamaran type boat mechanically propelled by an outboard motor comprising two floats, which are identical, coplanar and parallel, and a seat of the motor which are maintained rigidly together. Two transverse bars perpendicular to the axis of the floats are connected at their centers by a longitudinal member extending between the two floats. Two lateral bows fastened with the seat extend on either side up to the front transverse bar lower and upper fairings completing the boat by constituting a place to sit and for control.
U.S. Pat. No. 5,354,222 discloses a water rescue sled having a buoyant body for towing an incapacitated victim behind a personal watercraft. A coupling attaches the buoyant body to the personal watercraft providing at least two degrees of freedom so as to minimize stress to both the personal watercraft and the rescue sled during use. The water rescue sled further comprises a plurality of ties for securing a victim to the buoyant body. The sled may function as a backboard for maintaining the spine in a straight and immobile configuration during transport if the ties are configured as handles. Ropes or the like may be attached to the ties and placed over the victim so as to maintain the victim safely upon the upper surface of the buoyant body.
U.S. Pat. No. 6,352,460 discloses a neutral buoyancy recovery device (NBRD) for retrieving an immobile object or incapacitated individual from a liquid area using neutral buoyancy. The NBRD is easily submerged and placed under an object to be recovered. At least one bladder attached to the NBRD is inflated, manually or by compressed gas, to create positive buoyancy and propel the object to the surface. The bladder(s) is located in a space between two panels, which are connected to form one unit. Various straps and ropes are used to stabilize the object or individual as the NBRD is maneuvered through the surface.
U.S. Pat. No. 7,137,350 discloses a catamaran having a pair of spaced-apart pontoons, each having a forward tapered and a rearward end. An underwing is affixed to the pontoons and spans therebetween. A platform is pivotally connected to the underwing and conforms to the pontoons at their forward tapered end or their rearward end. A power assembly is connected to the platform for adjustment to/from a stowed position to/from a plurality of working positions, including below the waterline. The platform may also carry a deployable extending ramp with a walkway formed by floating for protecting the craft from damage.
U.S. Pat. No. 5,809,923 discloses a buoyant and adjustable vessel for navigation in shallow and deep waters without changing the total vessel weight. The sea keeping characteristics and dynamic stability of the vessel are also managed by changing the shape of the buoyancy and controlling corresponding wet vertical depth necessary for safe operations and navigation.
U.S. Pat. No. 7,247,070 discloses an ice rescue craft including a plurality of locking raft sections that are foldable for storage and transport. A drive unit includes a drive wheel driven by an electric motor which may include a plurality of spikes configured to engage ice and a plurality of paddles that are centripetally urgeable outward to pull the rescue craft through water. A forward raft section may include a pair of outboard pontoons to provide stability and minimize lateral rocking. An aft raft section includes at least one rudder mounted to a plate on a pivoting, biased system. The rudders automatically fold upwardly when on solid surface or downwardly while in water.
U.S. Pat. No. 5,248,271 discloses a built-up watercraft including a body consisted of three base boards hinged together and bilaterally supported on two floats by two wings, two propeller runners bilaterally coupled to a transmission mechanism mounted on the body at the back, a rudder assembly fastened to the body below the transmission mechanism, a steering wheel assembly mounted on the body at the front and driven to adjust the direction of the rudder assembly. The three base boards of the body and the wings are folded up and formed into the shape of a case as the watercraft is not in use. Connecting tubes are made on the wings and the body for permitting a plurality of watercrafts of the same structure to be connected in series as well as in parallel by flexible connecting rods.
Thus, what is lacking in the art is a means for moving a large amount of people or supplies using a propulsion system as low cost and reliable as a PWC.